IPMC7xx ISA Bus Resources
http://www.motorola.com/computer/literature 1-39
1
ISA DMA Channels
There are seven ISA DMA channels in the PIB. Channels 0 through 3
support only 8-bit DMA devices while Channels 5 through 7 support only
16-bit DMA devices. These DMA channels are assigned as follows:
Note Because the Z85230 is an 8-bit device and Channels 5 and 6
are 16-bit DMA Channels, only every other byte (the even
bytes) from memory is valid.
Table 1-22. PIB DMA Channel Assignments
PIB
Priority PIB Label Controller DMA Assignment
Highest Channel 0 DMA1 Serial Port 3 Receiver (Z85230 Port A Rx)
Channel 1 Serial Port 3 Transmitter (Z85230 Port A Tx)
Channel 2 Floppy Drive Controller
Channel 3 Parallel Port
Channel 4 DMA2 Not available - Cascaded from DMA1
Channel 5 Serial Port 4 Receiver (Z85230 Port B Rx)
Channel 6 Serial Port 4 Transmitter (Z85230 Port B Tx)
Lowest Channel 7 Not Used